1. Field of the Invention
The present invention relates to a method of controlling a fuel supply unit of a fuel cell system, and more particularly, to a method of correcting a flow rate in a fuel supply unit.
2. Description of the Related Art
Conventional fuel cell systems include a fuel pump for supplying fuel to a reformer or a stack. The fuel pump is driven by a motor so as to generate a pumping force, thereby supplying the fuel to the reformer or the stack.
When the fuel is supplied by the fuel pump, it is necessary to increase or decrease the quantity of fuel supplied as occasion demands. In one method, an output of the fuel pump is increased or decreased by changing the amount of power applied to the fuel pump, whereby the amount of the fuel is changed. In another method, a flow meter and a controller for controlling the flow meter are installed in the fuel pump, the flow meter measures the flow rate of the fuel, and the controller transmits a signal as the measurement result, thereby controlling the fuel pump in accordance with the processed signal.
The former method of controlling the flow rate is advantageous in that the fuel cell can be manufactured at low cost thanks to the simple construction thereof, but is disadvantageous in that a high-precision flow rate control is not anticipated. On the other hand, the latter method of controlling the flow rate is advantageous in that it is possible to perform a high-precision flow rate control, but is disadvantageous in that the flow meter and the controller for controlling the flow meter are additionally provided, thereby increasing production cost and the size of the entire system. Therefore, there is a desire for a fuel cell system capable of realizing a high-precise flow rate control at a low cost.